The present invention relates to a device for supplying breathing gas, particularly for divers, of the type which comprises, in a housing, a means for feeding a breathing gas which includes a pressure-reducing valve for the incoming gas, attached to a piston sliding in the bore of a cylinder and actuated by a longitudinally moving piston rod, which in turn is controlled by a lever whose one free end makes contact with a soft diaphragm, and with said housing having an opening to an inhaling-exhaling conduit ending in a mouthpiece.
This type of device makes it possible to supply to the user quantities of breathing gas which are just sufficient and which are at the pressure of the environment, thanks to the diaphragm which reacts to the varying ambient pressure, while the device for feeding breathing gas, which is similar to a pressure-reducing valve, ensures the final reduction of the pressure of the breathing gas whose pressure had been previously reduced to a moderate value in the first pressure-reducing stage which is mounted on the tank containing breathing gas for the user.
But, each time they occur, i.e. at the breathing rate, the drops in the gas pressure, which are necessary for the functioning of the gas-feeding device, cause a considerable amount of cooling. Problems caused by that cooling action at the first stage of pressure reduction can be handled easily, but the same is not true for the breathing device which comprises, as has been stated above, a complete set of moving parts. These various parts become cold and if, for example, a diver is moving in water whose temperature is close to 0.degree. C., the temperature of some of the moving parts may drop below 0.degree. C. Since the air exhaled by the diver is saturated with moisture, this moisture is converted to ice when it makes contact with the cold parts and as a result the parts "freeze" because of icing. Such frozen parts in the gas feeding device may cause the valve to stay open permanently and breathing gas is continually fed into the housing, which produces considerable breathing difficulties for the diver.